The script for "Stigma" stated that the NX-class conference room, which first appears in that episode, was to be a "re-dress of [an] existing set." [1] Ultimately, the NX-class conference room was represented with a redress of the set for the NX-class mess hall. (ENT: "The Forge" audio commentary, ENT Season 4 Blu-ray)

An external shot of Enterprise's conference room shown in "United" would place it on E-deck. For that shot, though, the room's placement on board the ship wasn't scripted.

While the Interspecies Medical Exchange was hosting a conference at a facility on the surface of Dekendi III in 2152, an area of the building which was reserved for a Vulcan contingent included a Vulcan conference room. At one point during the IME conference, this room was used for a hearing attended by not only Vulcan doctorsStrom, Oratt, and Yuris but also EnterprisecaptainJonathan Archer and Vulcan Sub-CommanderT'Pol. The hearing mainly regarded Pa'nar Syndrome and T'Pol having recently been recalled to Vulcan due to concerns over the fact she had contracted the syndrome. However, Dr. Yuris also took the opportunity to concede several revelations, including that he also had Pa'nar Syndrome and that T'Pol was not responsible for having initiated a mind meld that had led her to acquire the affliction. (ENT: "Stigma")

The script for "Stigma" specified that the Vulcan conference room was to be a "re-dress of the Medical Suite," referring to another area of the Dekendi III conference facility's Vulcan division. [2]

Later that year, Captain Archer and CommanderCharles Tucker III waited in Enterprise's conference room prior to the arrival of Vulcan AmbassadorSoval and Sub-Commander Muroc. After the pair of Vulcan visitors were escorted into the room by T'Pol, a short meeting was held by all five there, prior to Archer and T'Pol visiting the planet Weytahn. Once they returned, they as well as Soval and Muroc met again in the conference room, having arranged to escort Soval into peace talks with the Andorians on Weytahn. After he together with T'Pol and Archer managed to meet with Andorian Commander Shran, all four, along with Muroc, attended another meeting in the conference room, Shran suggesting a toast to mark the start of the peace talks. (ENT: "Cease Fire")

Later that year, a briefing was held in Enterprise's conference room. Sub-Commander T'Pol, LieutenantMalcolm Reed, EnsignsTravis Mayweather and Hoshi Sato, as well as DoctorPhlox were in the room when Commander Tucker arrived. They chatted about the upcoming briefing but stopped when Captain Archer entered the room, with news that a probe had recently committed an attack on Earth. Also, Archer was told, via the room's companel, that the ship was receiving a transmission from AdmiralForrest. Lastly, the captain ordered Ensign Mayweather, the vessel's helmsman, to set a course for Earth at warp five. (ENT: "The Expanse")

On Lorian's recommendation in 2154, he and Karyn Archer had a discussion with Captain Archer and T'Pol in the conference room aboard Enterprise shortly after the two groups met each other for the first time. (ENT: "E²")

Shortly thereafter, Enterprise's conference room was used for a meeting between Commander Tucker, Phlox, Soval, Stel, and V'Las. They discussed evidence that Stel was guilty of the embassy bombing and talked about the fact that the "evidence" had been obtained by Soval via a Vulcan mind meld, although that technique was generally considered highly distasteful by Vulcan society. (ENT: "The Forge")

Soon afterwards, the conference room was used by Commander Tucker, Soval, and Shran. Soval warned Shran about an imminent invasion of Andoria that the Vulcan High Command was planning. Shran was extremely skeptical of this news but eventually decided to discuss the claim with his superiors. Tucker advised Shran to be expedient about doing so. (ENT: "Kir'Shara")

Enterprise's conference room darkened, while being used by Archer, Shran, and Gral

In the final draft script of TOS: "Court Martial", a scene which is set in one of the briefing rooms aboard the Constitution-classUSS Enterprise had a scene heading which indicated it was to be set in a "conference room". This was changed to "briefing room" by the time the revised final draft of the script was issued.